The present invention relates to an actuator element comprising a housing, a drive arranged in the housing, a movably mounted rod operatively connected to the drive to execute a force transmitting movement, and at least one means for detecting position, and to a modular system for producing an actuator element according to the invention.
Actuator elements for operating actuator devices such as flap valves, rotary slide valves or other valves are known in the prior art. For many applications, it is necessary to detect and monitor at least the end positions of a piston rod, which is connected to the drive of the actuator element. It is known from EP 0 345 459 B1 that an electric switch, which can be operated as a function of the position of the piston rod in relation to the housing, may be provided inside a pressure chamber of a pneumatic actuator element. When the piston rod reaches a predetermined position, the switch is actuated and thus delivers an electric signal. The switch is intentionally located in the pressure chamber of the pneumatic actuator element to thus be protected from soiling and corrosion due to corrosive media. Likewise, those skilled in the art are familiar with actuator elements with which the position detection is performed based on the reduction in the signal of a loop potentiometer.
One disadvantage of these solutions is the susceptibility of this contact-controlled end position detection to wear as well as the resulting susceptibility from the standpoint of a reliable signal output. Likewise there is the risk of corrosion of the contacts or the loop contacts of the potentiometer, especially in contact with chemicals or corrosive material. Another disadvantage of the loop potentiometer is the temperature drift that occurs with large changes in temperature and the consequent unreliability of the signal output.